<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style type="text/css">
        * {
            margin: 0;
            padding: 0;
        }

        #container {
            width: 600px;
            height: 400px;
            border: 3px solid #333;
            overflow: hidden;
            position: relative;

        }

        body {
            padding: 20px;
        }

        #list {
            width: 4200px;
            height: 400px;
            position: absolute;
            z-index: 1;
        }

        #list img {
            float: left;
        }

        #buttons {
            position: absolute;
            width: 100px;
            height: 10px;
            z-index: 2;
            transform: translate(250px, 380px);



        }

        #buttons span {
            display: inline-block;
            cursor: pointer;
            width: 10px;
            height: 10px;
            border: 1px solid #fff;
            border-radius: 5px;
            background: #333;
            margin-right: 3px;


        }

        #buttons .on {
            background-color: orangered;
        }

        .arrow {
            display: none;
            position: absolute;
            cursor: pointer;
            line-height: 39px;
            text-align: center;
            font-size: 36px;
            font-weight: bold;
            /*width: 40px;
            height: 40px;*/
            z-index: 2;
            top: 180px;
            display: none;
            background-color: RGBA(0, 0, 0, .3);
            color: #fff;


        }

        .arrow:hover {
            background-color: rgba(0, 0, 0, .7);
        }

        #container:hover .arrow {
            display: block;
        }

        #prev {
            left: 20px;
        }

        #next {
            right: 20px;

        }
    </style>
    <script type="text/javascript">
        /*获取元素*/
        window.onload = function () {
            var container = document.getElementById("container");
            var list = document.getElementById("list");
            var buttons = document.getElementById("buttons").getElementsByTagName("span");
            var prev = document.getElementById("prev");
            var next = document.getElementById("next");
            var index = 1;

            /*显示按钮的函数*/
            function showButton() {
                for (i = 0; i < buttons.length; i++) {
                    if (buttons[i].className == "on") {
                        buttons[i].className = "";
                        break;
                    }
                }
                buttons[index - 1].className = "on";


            }


            /*第一步：封装*/
            function animate(offset) {
                var newLeft = parseInt(list.style.left) + offset;
                var time = 300;/*位移的总时间*/
                var interval = 10;/*位移的间隔时间*/
                var speed = offset(time / interval); /*每次的位移量*/
                function go() {
                    if ((speed < 0 && parseInt(list.style.left) > newLeft) || (speed > 0 && parseInt(list.style.left) < newLeft));
                    list.style.left = parseInt(list.style.left) + speed + "px";
                    setTimeout(go,interval);
                }
                   else{
                    list.style.left = newLeft + "px";
                    if (newLeft > -600) {
                        list.style.left = -3000 + "px";
                    }
                    if (newLeft < -3000) {
                        list.style.left = -600 + "px";

                    }

                }
            }
            go();
        }

        prev.onclick = function () {
            if (index == 1) {
                index = 5;
            } else {
                index -= 1;
            }

            showButton();
            animate(600);

        }
        next.onclick = function () {
            if (index == 5) {
                index = 1
            } else {
                index += 1;
            }

            showButton();
            animate(-600);
        }




        for (var i = 0; i < buttons.length; i++) {
            buttons[i].onclick = function () {
                if (this.className == "on") {
                    return;
                }
                var myIndex = parseInt(this.getAttribute("index")); /*获取自身的index*/
                var offset = -600 * (myIndex - index);
                animate(offset);
                index = myIndex;
                showButton();
            }
        }



            

    </script>

</head>

<body>
    <div id="container">
        <div id="list" style="left: -600px;">
            <img src="./img/5.jpg" alt="">
            <img src="./img/1.jpg" alt="">
            <img src="./img/2.jpg" alt="">
            <img src="./img/3.jpg" alt="">
            <img src="./img/4.jpg" alt="">
            <img src="./img/5.jpg " alt="">
            <img src="./img/1.jpg" alt="">
        </div>

        <div id="buttons">
            <span index="1" class="on"></span>
            <span index="2"></span>
            <span index="3"></span>
            <span index="4"></span>
            <span index="5"></span>
        </div>
        <a hre="javascript:;" class="arrow" id="prev">&lt;</a>
        <a hre="javascript:;" class="arrow" id="next">&gt;</a>

    </div>
</body>

</html>